Signal storage tube



May 17, 1960 Y J. E. OTTO 2,937,313- SIGNAL STORAGE TUBE Filed MarchIfO, 1959 2 Sheets-Sheet x Fig. I

Invenfar:

Jm/u'm E. Oilo y 1960 J. E. OTTO SIGNAL STORAGE TUBE Filed March 30,1959 2 Sheets-Sheet 2 In venfor:

J c/u'm E 0210 2931313 SIGNAL STORAGE TUBE Joachim E. Otto, Ulm(Danube), Gerinany, assignor to The present invention 7 relates tostoring ofelectrical United. States signals and, more particularly, to asignal storage-tube 1 having a substantially strip-shapedtargetelectrode ,and

oneor two electron guns used for producing both= writing and readingbeams.

In the following discussiomeachtype; of signal storing while each kindof signal target electrode. r 1 s The necessity ofstoring-electrical-signals fora limited period of time arises, forexamplegif the video frequency signal band in a radar? set has first tobe.com pressed prior to its transmission, for the purposenoftransmission by means having aba'nd width which is narrower than,saidjsignal band. -Signal storage tube are particularly suitable forthis purpose. 1

In storage tubes for this andjother similar purposes, wherein signalsare recorded on target electrodes, it is usual practice-tocausean-electron beam which has been intensity-modulated by the signalvoltage to travel once or several times over said target electrode usingsuitable deflection means, whereby changes in the electrical charges onsaid target electrode are stored, said changes being dependent on'the'instantaneous-intensities of the respective beam-modulatingsignals. The; methods of producing such changes are well known. Withknown.

storing electrode is called a cathode ray ,tube is briefly calledastorage tube]? :1?

storage tubes, the intensity modulation of the electron beamis obtainedby means of cathode control or Wehnelt electrode control. t v

In said storage tubes, both the pick-up and the oblitera' tion of thestored'sig'nals are likewise'obtained by means of an electron-beamwhich, however, has a constant-intensity and which iscaused to'travelwith the aid of de flecting means at suitable-velocity once over thesame track onthe target electrode along which'the first elec- .tron beamtravelled'when writing the respective signals, whereby signal voltagevariationsare obtained in aworking resistance insertedin the circuit ofa signal collecting plate on the side ofTthe targetnelectrode facingaway 'from the electron gun. Intheiramplitude distribution,

the above-mentioned voltage variations follow the stored chargedistribution on the track of the target electrode and, in this way, theyrepresent the'signals stored thereon.

When using the above type of=storage tube, there ap-v pears thedisadvantage that, due to' the. nonlinearity of the beam currentcharacteristic of the Wehnelt electrode potential, the relationshipbetween the control voltage and the beam current is also nonlinear,whereby the amplitude of the .signals to be transmitted is distorted; Inaddition, it is, often necessaryin lithe operation of such storage tubesthat a directcurrent component be super- I imposed tothe-alternating-current' component of the beam current'including the,signal; Due to the nonlinear shape of-the curve'characteristic, anoptimum ad.-

justment of the operating characteristic ofzgthe storage .tube is notreadily possible in case of high amplitude als Moreover, the outputsignal compressedbandwidth in this type of storage tube also contains,even in the absence of input signals, the compressed noise spectrum ofall of the preceding stages of the apparatus.

Furthermore, it should be borne in mind that the range of informationwhich can be stored ,is rather "small.

With other embodiments of storage tubes which are suitable for theabove-mentioned purpose, the changes in either the electrical charges orin the electrical properties of the target electrode are obtained by.applying the signal voltage to a collector electrode or to a gridlikeelectrode, disposed immediately before or directly .on the targetelectrode, or by applying said signal voltage to the ,target electrodeitself in cooperation withan electron beam of constantintensity which iscaused to' travel once or several times overv said target electrode bysuitable deflecting means. The methods causing 'said changes in thetarget electrode of such tubes are likewise. known per se. With saidstorage, tubes, thepickup'iand, if required, .also the obliteration ofthe stored signals are done by means of an electron beam having aconstant intensity, which electron beam is also swept by deflectingmeans once at a suitable velocity over the same track on the targetelectrode over which the first t electron beam was swept when writingthe'respective .rUsing this type of storage tube, it-"has, likewise,been found "disadvantageous that the output signal' of compressed bandwidth, even in the absence of input'si'gnals',

always contains the compressed noise spectrum of the] preceding stages.In addition, it should be taken into consilderation that the range ofinformation is also smal Embodiments of the two forenientioned' groupsof storage tubes have been known, in which the electron: beam-or beamshave a circular or rectangular cross section. Furthermore, cathode raytubes have been known having anelectronbeam of circular cross see tion.In-these tubes, the electron beam issubjected to adeflectionwhich isdependent on the amplitudeof the signal voltage fed to-the-tube, asfinoscillog'raph: tubes.

' 'It' is 'an object of the present invention to provide a? storagetubein which the'aforementioned disadvantages are overcome bya suitable'design of the electron beam and by means of a dilferent control system.In the following, the deflection ofthe electron beam, dependent on thesignal voltage, will be explained as being distinguished from thecyclical electron beam sweep. 7

It is another object of the invention to provide a' storage tube inwhich the electron beam 'isidesigned as a band-shaped electron beamhaving a cross-sectional ratio of at least 1:5, so that thelongercrossksectional dimensions of the electron beams are orientedperpen dicularly to the longitudinal extensionof; the target electrodeover which the electron beams travel; Means'a re provided by which the"writing beam, depending on the signal to be stored, is deflected inthedirection of the longer cross-sectional dimension .of the, electronbeam;

and the band-shaped beams have a=constantmean intensity for onedeflecting operation whether a writing cycle or reading cycle. 'T 1;; 7-Still further objects and the entire scope of applicability of thepresent invention will become apparent from V 5 the detailed descriptiongiven hereinafter; it should be understood, however, that the detaileddescription v and those skilled in the art from this detaileddescription.

In the drawings:

Figure 1 is a fragmentary schematic showing of a band-shaped beamimpinging on a target electrode, and

Figure 2 is a partial perspective view showing a storage tube electrodearrangement according to the invention.

Referring in detail to the drawings, Figure l schematically shows aportion of an elongated target electrode on which two tracks 3 and 4adjacent one another are provided side by side and a signal collectingplate 5 is arranged on the side ofthe target electrode opposite theelectron-emitting source, in the circuit of which a load resistance '6is inserted. -Al'so forming a part of the circuit is an electron beam1-haVingan approximately rec'- 't-angular cross section, said beam beingcaused to travel a pair of beam deflection electrodes 2 to modulate theposition of the beam on the target. To avoid crowding of the drawing,the conventional collector electrodejs omitted. As long as no signalvoltage is applied to the deflecting plates 2, the electron beam 1 willtravel along the track '3, but .when a signal voltage is applied to thedeflecting plates 2, the electron beam 1, while being swept over thetarget electrode in the direction of the arrow, will be deflected fromthe track 3 to the track 4, whereby the relative electrical state ofcharge of the two tracks 3 and 4 of the target electrode will bechanged, said state of charge being indicated by shading in Figure 1.

, For pick-upjof the signals stored in the target electrode, there isused also an electron beam 1 having an approximately rectangular crosssection, said beam being produced eitherby means of the same electrongun used for the signal writing electron beam, or by means of anotherelectron gun, whereby said second beam (not shown) is swept over thetarget electrode at a suitable velocity by conventional deflectingmeans. The longer cross-sectional dimension of the electron beam pickingup the stored signals should be designed such, that -it extends from theinner edge to at least the outer edge over the entire width of onetrack.

Figure l shows an arrangement having two similar tracks. If, with saidarrangement, theelectron pick-up beam is caused to travelalong the track3, the stored signal will be represented by the gaps on :said track,whereas, if the electron pick-up beam is swept along the track 4, thestored signals will be represented on said latter trackjby the spotscharged by the deflected signalwriting electron beam. With the use ofeither of the two aforementioned systems, pick-up voltage variationswill appear in the load resistance 6;, said variations corresponding tothe stored signals, whereby the polarities of the voltage variations inthe load resistance, however, are opposite in the two possibly differentpick-up tracks. The two tracks 3 and 4 may be designed to be eithersimilar to or different from one another.

Obviously, the track on the target electrode, from which no storedsignals are to be taken up, need not have any storing action which meansthat it may be, for instance, a collector electrode.

Furthermoregit is evident that the track designed to be a collectorelectrode need not be in the plane of the track comprising the target"electrode. On the contrary, the track designed to be a collectorelectrode may be arranged so that it is shifted from the plane of thetarget track in the direction 'of the electron emitting source "as wellas in the other direction.

In case of similar design of the two tracks, it "will be advantageousfor various purposes, if either "track has its own signal collectorplate electrically insulated from the signal plate of the other track,whereby a load resistance "can be inserted in the 'ci'riiuit at eithersignal plate. It, with the use of the abovementioned target electrode,the stored signals are picked up from the two tracks by means of anelectron beam having a band-like cross section, the longercross-sectional axis of which reaches at least over the entire width ofthe two tracks, tWlO paraphased output signal voltages will be availableat the two load resistances.

In the above mentioned embodiments of target electrodes employed in thestorage tubedesigned in accordance with this invention, the two tracksmay be arranged with their long sides adjacent one another and spaced ata suitable distance, for the purpose of fully suppressing the noiselevel in the input signal of the storage tube or for the purpose ofobtaining a threshold value.

It is evident that the above described embodiments of the storage tubeaccording to this invention are not confined to arrangements with lineartracks, i.e., the tracks may'als o be circular.

Figure 2 schematically shows the essential components of the embodimentof a signal storage tube having an annular target electrode, thestructure of which is principally the same as that of the targetelectrode shown in Figure 1. The rneans for obtaining a strip-like beamwill be explained with reference to Figure 2.

An electron beam having a circular cross section is first produced bymeans of both a cathode 11 and a symmetrically designed Wehnelt cylinder12, said electron beam being adapted to be focussed onto the tracks ofthe target electrode by means of symmetrically designed electrodes 13,14,-1.5, representing an electron lens. The electron lens 13, 14, 15,has been designed as an electrostatic single lens. This electron lensmay also be designed as an electrostatic accelerator lens or a magneticlens. In the embodiment of Figure 2, the electron beam is circularlyswept by means of a pair of deflecting coils (not shown), althoughelectrostatic deflecting means may be employed. The swept electron beam,having a circular cross section,- is spread in a dir'ection radial withrespect to the axis of the electron gun by "means of the annularelectrostatic cylinder lens 16, 17, 18, which produces an annularcylindrical field, so that that the electron beam 10, when impinging onthe target elect-rode 24, has an approximately rectangular Crosssection. In the embodiment of Figure 2, the ann'ula'r cylinder isdesigned as an electrostatic single lens. An annular electrostaticaccelerator lens may, likewise, be used, said lens producing anannular-cylindrical field. The electron beam, which is spread apart byannular deflection means comprising two rings 19 and 20, is alsoradially deflected in accordance with the signal to be stored. Thetarget electrode maybe designed as shown in "Figure l, iSe.-, 'it mayhave two 'side-by-side annular trac'ks. Reference numbers 22 and 23 areinterconnected collector electrodes. On the back side of the targetelectrode, there 'is provided'a metallic annularsignal plate 25 which isreturned to'g'rou'nd potential via a resistance 26. When the readingbeam sweeps over the target electrode, the signal voltage regained fromstorage will cause a voltage "drop 'acrossfthe resistance 26. Obviously,the various design :possibilities for the target electrode, as shown inFigure 1', "may, likewise, be applied to the annular target electrodeillustrated in Figure-2.

The storage tube according to this invent-ion has the advantages oflinear relationship between the amplitudes of the inputsignal voltageand'tho's'eofthe-output signal voltage since, as has been known per se,electrostatic defle'c'tion is linear. Moreover, the range ofintelligence which can be stored-may be of almost any magnitude, due tothe scanning principle accordin'g to this invention. Since th'e mean"intensities of both the writing beam and the reading beam are keptconstant, the working :point on the characteristic curve which ''is mostfavorable for the deflection can always be "adjusted independently ofthe input signal. Last, but not least, the system accordterized in thatthe electron beams have band-like crosssectional shapes with the longertransverse beam divmension disposed transversely of the longitudinaldimension of the target electrode over which said electron beams areswept; beam deflection means acting on the writing beam for deflectingthe latter transversely of the target electrode in response to signalsto be stored there- 'on so as to position-modulate the writing beam, andsaid beams having a constant mean intensity over each swept cycle.

2. A signal storage tube, as set forth in claim 1, characterized in thatthe target electrode comprises two parallel tracks the width of which atleast equals the longer cross-sectional dimension of an electron beam,the electron beam sweeping along one track when undeflected and beingdisplaced at least partially onto the other track when deflected.

- Y 3. A signal storage tube as set forth in claim 2, characterized inthat one track comprises a collector electrode, while the other'trac'kcomprises a storage electrode.

4. A signal storage tube as set forth in claim 2, characterized in thatthe two tracks comprise electrically mutually insulated storageelectrodes.

5. A signal storage tube as set forth in claim 3, characterized in thatthe two tracks have been arranged closely paralleltto one' another andmutually electrically insulated from each other.

I 6. A signal storage tube as set forth in claim 3,.

characterized in that the two tracks have been arranged fat a smalldistance from one another and electrically insulated from each other.

7. A signal storage tube as set forth in claim 2, charac- .terized inthat the target electrode has a single storing layer comprising bothtracks.

8. A signal storage tube as set forth in claim 1, charac- 6 V, terizedin that the intensity of the beam us'ed for the writing cycle isdifferentfrom the intensity of the beam used for the reading cycle. y i

9. A signal storage tube'as set forth in claim 1,- characterized in thatthe beam cross section during thereading cycle extends transversely ofthe target electrode'at least twice the width of one track.

10. A signal storage tube as set forth in* claim 1, characterized inthat the target electrode is annular and normal to the axis of the gun.

11. A signal storage tube as set forth in claim 10,

characterized by beam-shaping means between thesweep means and thetarget electrode for distorting the beam emitted by the electron gunfrom a beam of circular cross section into an elongated beam, the longerdimensionof which is radial as applied to the annular target electrode;and said beam deflection means comprising annular de-V said radialfiecting electrodes for deflecting the beam in direction. a

12. A signal storage tube as set forth'in claim 11,

characterized in that the beam-shaping means comprises an annularcylinder lens.

13. A signal storage tube as set forth in claim 11,

characterized in that said deflection means comprises annular concentricdeflection plates.

14. A signal storage tube as set forth in claim 13,

characterized in that said deflection plates compriseiseveral separatesections for the purpose of improving the sensitivity of deflection.

15. A signal storage tube as set forth in claim .11,

characterized in that the deflection means comprise several pairs ofconcentric truncated surfacesotrevolution disposed in spaced relationalong the tubeathe directly concentrically adjacent parts of which areapplied to the same potential; and that the parting lines between thepairs have been designed such, that the beam will be subject todeflection if there are diflerent voltages on said j spaced pairs. 7

References Cited in the file of this patent UNITED STATES PATENTS2,276,359

Von Ardenne :'Mar.' 17, 1942 2,887,612 Frenkel May 19, 19 59

